Agricultural harvesters such as combines, travel through fields of agricultural crop harvesting the crop.
The threshing, cleaning and separating mechanism inside the agricultural combine typically includes a rotor disposed inside a concave grating. Cut crop material is fed between the rotating rotor and the stationary grating to thresh and separate the crop.
The grain falls through holes in the grating and onto a sieve and/or chaffer in a cleaning shoe. Sieves and chaffers are generally planar sheets with holes in them through which air is blown. The air lifts the residue and carries it away to the end of the combine. The grain, being heavier, falls through the holes in the sieves and chaffers and is gathered in the bottom of the cleaning shoe to be conveyed to the top of the combine and deposited in a grain tank or grain reservoir.
Sieves and chaffers work best if the grain is evenly distributed across their width. When a combine travels on the side of a hill and the combine body tilts, the grain tends to accumulate on one side of the sieve/chaffer and the cleaning efficiency is reduced. For that reason, combines are provided with leveling mechanisms to level the sieve within the combine itself, or to level the whole combine by adjusting the relative height of the combine's wheels. To level the entire combine, leveling mechanisms are provided that lift or lower the front drive wheels, thereby tilting the combine body in a side-to-side direction until the sieves are horizontal. These combines are commonly called “side hill combines”.
This whole-combine system of tilting the combine body with respect to the ground causes problems for the crop residue spreading mechanisms. Most combines have crop residue spreading mechanisms with adjustable fans, vanes and other steering devices. These mechanisms are fixed on the rear of the combine and spread the crop residue side to side behind the combine itself. The purpose of the residue spreading mechanisms is to redistribute the crop residue evenly over the ground where it can be broken down and returned to the soil as nutrients.
As long as the combine body is parallel to the surface of the ground (such as when traveling on flat ground) the residue can be evenly distributed. When the combine is not parallel to the surface of the ground (such as when traveling on the side of the hill with the combine body tilted) the residue distribution is irregular. Instead of throwing the residue evenly to both sides of the combine, crop residue spreading mechanisms throw the crop residue into ground on the uphill side of the combine, and throw the crop residue way downhill on the downhill side of the combine. Again, this is due to the fact that the combine body has been leveled while it is traveling on the side of a hill.
What is needed is a method for permitting the combine to travel off-level on the side of the hill in order to provide better crop residue distribution while not compromising cleaning shoe operation too much.
It is an object of this invention to provide such a method.